Yes, Hawg is right. The bolt block is a game changer in how durable and reliable the bolt will be. The hand stops the "carry up" or rotation to battery. This is what makes a fanner a dangerous revolver in the hands of someone that is unaware of its function. Firing out of battery with a cap gun probably isn't as dangerous as with a cartridge gun but it's still not the "best" practice! There's also an action stop which positively stops the rearward travel of the hammer. This keeps the hand from being forced against the ratchet of a locked cylinder. It also allows you to have the same exact stopping point every time the action is cycled.
You can produce a very accurate action using these additions in a regular setup. That is why I use blocks, and stops in my service. Just the addition of a bolt block in an otherwise "correctly timed" revolver can change the accuracy of that setup and thus, put the action out of time.
The bolt drop is adjusted to drop at least 2 bolt widths before the notch. You don't want it to drop at half cock or you won't be able to load it (the short hand gives you more "room" for this part of the setup since it doesn't advance the cyl as much).
Lastly, coast (gun talk for inertia) is what allows the cylinder to get to battery.
I also "massage" the bolt head somewhat to allow for earlier entry into the notch than a standard bolt head. I also treat the right side of the bolt head to a cut that just allows the full width and depth of the head to be IN the notch. This protects the lock notch from the battering of fanning (also in my regular setup as well).
Mike
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